My Buick will not shift gears.
It is highly likely that you have a TH200-4R transmission in your Regal. The vacuum line to the modulator and the adjustment of the throttle cable can be checked. These will have the ability to prevent upshifts and downshifts of the transmissions. The valvebody may also be faulty. You may need to enlist the help of a mechanic to check these adjustments. The transmission if still not shifting correctly may need to be removed and rebuilt.
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